The invention is directed to a cutting tool with a cutter bit or a carving insert, which is held exchangeably in one-piece tool support and lies in contact with opposite jaws of the tool support that form a clamping gap, with prismatic clamping surfaces disposed in common with those of the jaws, and with a tightening screw for narrowing the clamping gap.
To achieve a high transverse stability in narrow square-nosed cutting tools with interchangeable cutting inserts, the provision of a further, separate element, namely a tensioning blade, in addition to the cutter bit and the tool support, is known (German Offenlegungsschrift 34 34 089). This tensioning blade is carried in the tool holder, can be shifted longitudinally and, when the tightening screw is tightened, is pressed forwards to clamp the cutter bit against the tool support. However, to realize this longitudinal shift, a relatively expensive, precise linear guiding system for the tensioning blade must be formed in the tool support. Moreover, the cutter bit must constantly be disposed, so that it is inclined to the carving or guiding direction.
In known tools of the initially described type (see German Patent 32 19 150), the clamping surface of at least one clamping jaw is provided with a reentrant syncline or convexity, which is preferably triangular in cross section and corresponds to the construction of the adjoining clamping surface of the cutter bit. Due to the doubly prismatic construction of the mounting section and, conversely, due to mutually opposite triangular grooves in the clamping surfaces of the cutter bit, the latter is held particularly well and securely despite transverse stresses. Moreover, an additional clamping screw is provided, which presses the clamping jaw, which can be dropped open, over the elastic resiliency measure against the cutter bit during the propping open process. Admittedly, in the position in which it is used, the clamping surface of the clamping jaw that can be propped open gradually rises relative to the clamping surface of the cutter bit towards the interior of the clamping gap, so that the actual clamping point is at an appreciable distance from the rear end of the cutter bit. However, because of the construction of the prismatic clamping surfaces, said clamping or tightening screw generates only force components, which are approximately perpendicular to the longitudinal direction of the clamping gap. A combined effect of the clamping force of the tightening or clamping screw and the actual clamping point, which is shifted forwards, is not brought about by these means.